From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E97A0C433F5 for ; Sat, 30 Apr 2022 12:05:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239633AbiD3MIa (ORCPT ); Sat, 30 Apr 2022 08:08:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34938 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238806AbiD3MI3 (ORCPT ); Sat, 30 Apr 2022 08:08:29 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C6925C663; Sat, 30 Apr 2022 05:05:04 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1BB9D60AF8; Sat, 30 Apr 2022 12:05:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF9E4C385AA; Sat, 30 Apr 2022 12:05:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1651320303; bh=tWlItz5i5kXdXuKnvQvNpU5f7HV/eMhhZ4OfG79KfB4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EWPWQ/+A8KiWNeEnnCkAKXMPSezGdtzp5Pu/mRwQ/MU866OQbmFsojF7i409gTuJu COUJKad1RdoM48RcXRCz1/y234ep+r8F5hVv3U8qnSyXd89g/SqzfONVpSS2CCu9eN CMKtf9Kko8TmVqrBl0bJ24rI3PoZ2XY2ikw7YirU= Date: Sat, 30 Apr 2022 14:04:59 +0200 From: Greg KH To: Mauro Carvalho Chehab Cc: Luis Chamberlain , Daniel Vetter , David Airlie , Jaroslav Kysela , Kai Vehmanen , Lucas De Marchi , Pierre-Louis Bossart , Takashi Iwai , alsa-devel@alsa-project.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org, mauro.chehab@linux.intel.com, Dan Williams Subject: Re: [PATCH v2 1/2] module: update dependencies at try_module_get() Message-ID: References: <3c7547d551558c9da02038dda45992f91b1f5141.1651314499.git.mchehab@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3c7547d551558c9da02038dda45992f91b1f5141.1651314499.git.mchehab@kernel.org> Precedence: bulk List-ID: On Sat, Apr 30, 2022 at 11:30:58AM +0100, Mauro Carvalho Chehab wrote: > Sometimes, device drivers are bound into each other via try_module_get(), > making such references invisible when looking at /proc/modules or lsmod. > > Add a function to allow setting up module references for such > cases, and call it when try_module_get() is used. > > Reviewed-by: Dan Williams > Signed-off-by: Mauro Carvalho Chehab > --- > > See [PATCH v2 0/2] at: https://lore.kernel.org/all/cover.1651314499.git.mchehab@kernel.org/ > > include/linux/module.h | 4 +++- > kernel/module/main.c | 35 +++++++++++++++++++++++++++++++++-- > 2 files changed, 36 insertions(+), 3 deletions(-) > > diff --git a/include/linux/module.h b/include/linux/module.h > index 46d4d5f2516e..836851baaad4 100644 > --- a/include/linux/module.h > +++ b/include/linux/module.h > @@ -620,7 +620,9 @@ extern void __module_get(struct module *module); > > /* This is the Right Way to get a module: if it fails, it's being removed, > * so pretend it's not there. */ > -extern bool try_module_get(struct module *module); > +extern bool __try_module_get(struct module *module, struct module *this); > + > +#define try_module_get(mod) __try_module_get(mod, THIS_MODULE) > > extern void module_put(struct module *module); > > diff --git a/kernel/module/main.c b/kernel/module/main.c > index 05a42d8fcd7a..9f4416381e65 100644 > --- a/kernel/module/main.c > +++ b/kernel/module/main.c > @@ -631,6 +631,35 @@ static int ref_module(struct module *a, struct module *b) > return 0; > } > > +static int ref_module_dependency(struct module *mod, > + struct module *this) This can be on one line, right? > +{ > + int ret; > + > + if (!this || !this->name) { > + return -EINVAL; > + } Did you run checkpatch on this? Please do :) > + > + if (mod == this) > + return 0; How can this happen? When people mistakenly call try_module_get(THIS_MODULE)? We should throw up a big warning when that happens anyway as that's always wrong. But that's a different issue from this change, sorry for the noise. > + > + mutex_lock(&module_mutex); > + > + ret = ref_module(this, mod); > + > +#ifdef CONFIG_MODULE_UNLOAD > + if (ret) > + goto ret; > + > + ret = sysfs_create_link(mod->holders_dir, > + &this->mkobj.kobj, this->name); Meta comment, why do we only create links if we can unload things? thanks, greg k-h